"An Intel-based iBook has been widely trailed to be unveiled next week. If you're anticipating speeds and feeds ahead of next week's keynote, we'll have to disappoint you. But sources close to Apple suggest that the many in the rumor mill have failed to illuminate the bigger picture - a strategy to makeover the iBook as a cut-price bait to lure switchers, with price points much lower than Apple has ever risked for a portable machine. In many ways, the strategy is risky, but with rival PC notebook laptop prices in freefall - Dell today offers a $499 [EUR 410] notebook - Apple may not have any choice but to embrace it."

This is from apple.com site : "Quartz Extreme functionality is supported by the following video GPUs: NVIDIA GeForce2 MX and later, or any AGP-based ATI RADEON GPU. A minimum of 16MB VRAM is required.". G3 iBooks (<=600MHz) didn't have 16MB of vram, so they upgraded them to Radeon 7500 with 32MB of vram.